Interconnected lightweight floor slabs



Sept. 29, 1959 INTERCONNECTED LIGHTWEIGHT FLOOR SLABS A. B. ENGWALL 2,906,113

Filed Jan. 3, 1955 N VEN TOR.

W I 7 y Andersfla/fifyvd/ i/Mmw llnited States Patent 6 INTERCONNECTED LIGHTWEIGHT FLOOR SLABS Anders Berti] Engwall, Sodertalje, Sweden, assignor, by mesne assignments, to Casius Corporation Limited, Montreal, Quebec, Canada Application January 3, 1955, Serial No. 479,589

Claims priority, application Sweden January 13, 1954 2 Claims. (Cl. 72--68) The present invention relates to an arrangement in roof and floor structures of the kind comprising selfsupporting concrete slabs placed side by side and connected to one another, and particularly in connection with lightweight concrete slabs.

It has been customary hitherto when employing selfsupporting lightweight concrete slabs in roof and floor constructions to connect each lightweight concrete slab to the adjoining slabs by filling mortar or some other hydraulic binding medium into channel-shaped recesses along the joints between the slabs. This method of joining is time consuming, however, and among other drawbacks it cannot be employed in cold weather. Furthermore, this method calls for special measures in connection with the production of the lightweight concrete slabs in order to obtain the recesses or grooves. In view of these difliculties, a need has long existed for a method of employing lightweight concrete slabs as a building material without it being necessary to join the separate slabs to one another by means of mortar joints.

Various other methods have also been proposed for joining lightweight concrete slabs to one another by nailing or the like. Although these methods may be satisfactory in the case of small buildings and for roofs having, for example, only one bay, they cannot replace armoring rods (continuity rods) cast into special jointing grooves which were formerly employed for joining or jointing lightweight concrete slabs for large roofs and floor surfaces. By large roofs and floor surfaces is meant those areas in which the length of a single concrete slab represents only a fraction of the total extent of the flat roof or floor surface, reckoned in the longitudinal direction of the separate slabs.

The lightweight concrete slabs are usually rectangular and when they are employed for roofs or flooring they are generally laid transversely between supporting walls or beams so that they are freely suspended over at least a part of their length. The end joints between the slabs run parallel to the supporting walls or beams and preferably immediately over, or at least in the vicinity of, the said walls or beams.

In the case of large roofs, it has been found in practice that it is necessary to ensure a firm connection between the lightweight concrete slabs that form a continuation of one another in their longitudinal direction and abut against each other at their ends. At the same time, in many instances, it is also desirable to produce a connection at other points between the slabs placed side by side so that the latter are not mutually displaced in their longitudinal direction. Connections of this kind have been previously produced by filling up the longitudinal grooves which are open at the top between the slabs with cement mortar; armoring rods being cast in the longitudinal groove transversely across the end joints in order to take up the tensile stresses between the slabs.

To enable this casting in, of the armoring rods, to be eliminated, it is obvious that special members will have to be provided to fulfill the same function, and such members must then be driven in tight by means of hammers', for example. These members must hold the slabs together firmly without the help of a binding medium. It should be noted here, however, that ordinary nails cannot be employed owing to the fact that their area is too small to enable the heavy pressure at the hollow edges (which may occur in such cases) to be taken up by the lightweight concrete material. For this reason, the desired connection cannot be suitably produced by means of nails in the ordinary manner.

The present invention has for its object to provide a solution for this problem and relates to an arrangement in roofs and floor structures of the kind built up from a plurality of lightweight concrete slabs which are freely suspended over at least a part of their length and are laid on supporting walls or beams which are separated from each other.

With the foregoing and other objects in view as will appear from a reading of the following specification and claims, the invention resides in the novel arrangement and combination of parts and in the details of construction and process of manufacture hereinafter described and claimed, it being understood that changes in the precise embodiment of the invention may be made within the scope of what is claimed without departing from the spirit of the invention. It will be further understood that my invention is susceptible of embodiment in many and various forms, some of which are illustrated in the accompanying drawing, and that the structural details or particular steps of the method herein set forth may be varied to suit particular purposes and still remain within my inventive concept.

Fig. l is a plan view of a roof or floor under construction and incomplete showing a series of slabs connected together by my improved method.

Fig. 2 is an enlarged isometric detailed view of my invention.

The main feature characterizing the arrangement according to the invention resides therein that in the joints between the lightweight concrete slabs which run substantially at right angles to the supporting walls or beams, sheet metal strips arranged edgewise and provided with vertical flaps projecting on both sides and penetrating into the lightweight concrete slabs, are driven in from the top. The sheet metal strips are hereby primarily driven in between the lightweight concrete slabs transversely across an end joint which is parallel to the walls or beams.

To render the invention more clearly understood one form of construction will now be described with reference to the accompanying drawing showing a perspective view of a small part of a roof composed of light Weight concrete slabs with one slab removed in order to show the sheet metal strip arrangement for holding the slabs together.

In the drawing 1 indicates the various lightweight concrete slabs in the roof or floor, all of which are rectangular and are laid in their longitudinal direction at right angles to the beam 2 or partition wall 7 supporting the roof of building 8, and across which the ends of the slabs abut against one another in an end joint 3 parallel to the supporting beam. Transversely over .the supporting beam and across the end joint 3, longitudinally extended sheet metal strips 4 arranged edgewise are driven into the joints between the lightweight concrete slabs 1 which run at right angles to the beam 2. The said sheet metal strips are provided with stamped out vertical flaps 5 bent out onboth sides at right angles to the sheet metal strip. These flaps 5, which have a free length which is substantially less than the width of the flap reckoned parallel to the plane of the sheet metal strip, penetrate into the lightweight concrete slabs 1 adjoining one another, whereby on being driven in, they form grooves 6 which are 'visible on the upper side of the slabs 1.

The sheet metal strips are supported by the slabs located on both sides, and it has been found that they can take up considerable stresses in the longitudinal direction of the slabs without the flaps exhibiting a tendency to lose their grip in the edge portions of the slabs.

To facilitate the driving of the sheet metal strips 4 into the joints between the slabs '1 lying in position, a block with a groove on its underside adapted to the upper edge of thesheet metal strip may be employed as an intermediate part so that the hammer is prevented from crushing the upper edge in particular of the sheet metal strip or damaging it in any other manner. I p

The shape of the sheet metal strips may, of course, be altered without changing their function. Thus, the flaps may be made semi-circular for example, and the whole sheet metal strip may have a T-form in cross-section, in which case the Tflanges will cover the edge portions of the slabs in question. The manufacture of the sheet metal strips may naturally be carried out in different ways and justify alterations regarding their shape. If so desired, the sheet metal strips may also be further secured in the joints by means of nails or the like driven in obliquely.

Advantageously the sheet metal strips may be so designed and arranged, as shown in the drawing, that the stamped-out flaps or wings are integral with the strip on each side of the crossing end joint 3 at that vertical edge of the opening left in the strip which is remote from the end joint 3. In other words, preferably, for optimum effects, the flaps are stamped out so as to be hinged on the far side of each opening reckoned from the end joint 3.

What I claim is:

1. In a roof structure a beam and a plurality of preformed substantially rectangular concrete slabs supported thereon, said slabs being positioned in coplanar relation with the edges thereof contiguous, said slabs being disposed in longitudinal and transverse rows, the joints between said slabs being continuous, both longitudinally and transversely thereof, said slabs having respective corners meeting at a common point over said beam, an elongated metal connecting strip disposed within the longitudinal joint betwen the longitudinal edges of said slabs and extending across said beam and between the slab edges, said connecting strip having flaps engaging within the body of all adjacent slabs thereby preventing longitudinal movement of said slabs with respect to each other and transmitting stresses from one slab to the other.

2. A roof structure as set forth in claim 1 in which the body of said strip is continuous and unperforated at the upper and lower edges so as to have maximum strength, and the upper and lower edges of said strip are positioned in the joints betwen adjacent slabs so as to be exposed from both the upper portion and the lower portion of the roof structure.

References Cited in the file of this patent UNITED STATES PATENTS 951,150 Russell Mar. 8. 1910 1,371,857 Calkins Mar. 15, 1921 1,863,734- Venzie June 21, 1932 2,257,001 Davis Sept. 23, 1941 FOREIGN PATENTS 46,931 Switzerland Dec. 14, 1908 248,420 Italy May 19, 1926 

